February 2007

The University is conducting a survey of all students to get your views on IT services and facilities. What would you like us to do and how could we do it better?There is a prize draw for all completed surveys – the top prize is an iPod video worth Â£180, and other prizes of iPod shuffles and print/copier credits are also up for grabs. If you prefer not to enter the draw the survey is completely anonymous.

Your feedback is essential to help us provide the IT services that students need and want to use. Please use the survey to let us know. The closing date for the competition is 23 March 2007.

Performance is worst at peak times of day (generally evenings) when more people are using ResNet.

Why is this happening?

Network traffic (bandwidth) on ResNet goes up every year. This year however it has shot up far more than ever before, probably due to the growing popularity of online video such as YouTube and other sites.

We have taken steps to cope with the increased traffic. The University recently moved to a higher capacity Internet connection (SuperJanet 5) and so we’ve been able to increase the total bandwidth available for ResNet. This is a good thing, and will provide better performance for everyone on ResNet.

In addition for many years we have had a traffic management system on the link between ResNet and the Internet. This works to divide up the amount of capacity fairly between all ResNet subscribers. If we don’t have any traffic management then just a few of the 4500 people on ResNet can fill our entire pipe.

We’ve bought a new higher capacity traffic management system to cope with the new higher traffic levels. However it hasn’t worked as well as we’d hoped and we’ve had problems getting it up and running. At the same time our old traffic management system is creaking badly – it’s pretty old and not working as well as it should.

Because of this for some periods, especially on Thursday 22nd Feb, we’ve been running without any traffic management at all. This means that just a few people on ResNet can generate massive amounts of traffic, and the performance for everyone else really suffers.

What we are doing

We’d like to get much better and more consistent network performance. This is our top priority at the moment.

We are aiming to provide:

up to 8 Mbit download speed

latency of 20-60ms to UK sites

0-2% packet loss

consistency at all times of day

These are all trade offs – eg we can increase the download speed (good for people downloading large files) but this would probably increase the latency (not good for gamers or Skype users). We are trying to get the right balance. Sometimes we’ll tweak the settings, get it a bit wrong, and this will temporarily make things worse for some or all people. We’re very sorry about this, but please bear with us while we try to improve matters.

What you can do to help

You can help by

giving us some feedback on how well ResNet is performing for you,

keeping your usage low where you can

If you would like to let us know how well ResNet is working for you, please email resnet-help@bristol.ac.uk . Please include details of what you were doing and when you tried it.

To reduce your bandwidth usage if you have any form of peer to peer filesharing program (eg Bittorrent, eMule or similar) then shut them down as soon as you finish using them. Don’t leave them running in the taskbar all the time, as they generate huge amounts of traffic even when you personally aren’t downloading a file.

You can see your own usage by looking at Manage My ResNet. Remember we have a fair usage policy on ResNet where you can use transfer 10GB of data per week, and if you go over that you will be warned and then your usage will be restricted.

If we don’t have the traffic management in place it is much easier to go over the 10GB limit, so make sure you keep it under control.

We’re currently having some strange problems with the ResNet network resulting in sporadic performance. We’ve also seen some loss of offsite connectivity from ResNet.

We apologise for this, and we’re working hard to identify and resolve the problem.

More info will appear here as we get it.

Update 2007-02-23 – 11:40amWe seem to have managed to persuade the network to use the primary link, bandwidth shaping and all.Â However, we’re not confident enough in it to leave it in place over the weekend – so we’re looking at alternatives.Â

Update 2007-02-23 – 9am
Things are a little better, but they’re still not 100% stable. Our bandwidth management box fell over at about 3:45am this morning, causing the ResNet external traffic link to flip over to a backup link. We’ve restarted the bandwidth management box, although we’re having a little difficulty getting the network to switch back to using it.

At 10am this morning, we increased the maximum upload speed that each user can use on ResNet. We’re hoping that by allowing you to upload to the internet quicker, skype (and other VOIP applications) will become more reliable.

For info, the maximum download speed is currently set to 8Mbps, and the maximum upload speed has been increased from 2Mbps to 8Mbps (per user).

We will be keeping an eye on the traffic graphs and the packet loss/latency to make sure that this doesn’t cause any unforseen problems.

Don’t forget that uploads are included in your weekly traffic allowance, which you can check online keep an eye on your usage so that you don’t get caught out!

We are advertising a newly created full-time job for a Systems Specialist (Wireless & VPN). The job will be working alongside the rest of the ResNet team, but concentrating on our wireless services on campus rather than ResNet in the halls.

The problems we were experiencing with our new bandwidth management appliance (seeÂ bandwidth-management-teething-problems) seem to have highlighted a design flaw in the appliance itself.Â We’re working with the vendor to fix the problem, although we’re not expecting a patch from them for another two weeks or so.

Latency and packet loss are now back to the same levels that they were in January.Â However, these levels are still much higher than they were at this time last year.Â This is mainly because there’s a *lot* more traffic on ResNet than there was this time last year!

We will be making some changes next week which we hope will improve the situation further, we will be documenting details of the changes (Most importantly the details of the times when we put them in place) on the blog.

We’ve set up a new category for bandwidth related posts, so if latency/packet loss etc is of special interest to you (eg if you’re a gamer) you might want to keep an eye on theÂ bandwidth management category.

Our existing bandwidth management appliance is getting a little long in the tooth and whilst it can cope at the moment, it isn’t able to scale to match our needs for the future. So we’re replacing it, and over the last couple of days we’ve been trialing the new system.

Initial reports are mixed. Some users of services such as Skype have reported improvements, others have seen things get noticably worse. Eg at peak times last night, the latency on the network increased substatially compared to our previous solution.

One side effect is that the new system allows people much more “upload” bandwidth during off-peak times than we had anticipated. This seems to have caught out a few people who had left their P2P applications running, and caused them to go over their weekly bandwidth quota.

As this was unexpected, we have taken the decision not to transfer anyone to the restricted network on Monday. However, you do still need to keep an eye on your bandwidth usage as we are likely to go back to using the restricted network on the 12th Feb. Don’t forget that even if you’re not downloading anything, your P2P software may be uploading to other people. The best thing to do is to shut it off if you’re not using it!

We’re still learning about the new system, working closely with the suppliers to tweak it so that we get the best possible performance out of it for our environment. We think last nights latency problems were caused by a configuration oversight, which we will look into as soon as possible next week.

For the moment though, we have moved the network back to our previous bandwidth management appliance and we intend to leave it that way over the weekend.

We’re sorry for any inconvenience caused while we’re finding our feet with the new appliance. We hope that any problems will be short lived, and in the longer term you should notice an improvement in the quality of your network connection.

Microsoft released its new OS, Windows Vista, to consumers on Tuesday 30th January 2007. New machines are only just shipping with Vista installed so there can’t be many of these wanting to connect to ResNet just yet. We are however getting an increasing number of requests from people wanting to upgrade to Vista from XP.

We have been ‘playing’ with pre-release versions of Vista for many months and have found it to run quite sluggishly on even high end hardware so would discourage people spending their money at this time as they may be disappointed. BTW, the released version is not too sporty either 😉
Another problem, as the title of this blog suggests, is that McAfee have only just release a production version of Virus Scan Enterprise (VSE) 8.5i, which supports Vista. We are currently testing VSE 8.5i with Vista, XP and the management agent, ePolicy Orchestrator so that we can be confident that there won’t be any problems.

Once the testing of VSE 8.5i has been completed we need to modify the registration process to allow Vista onto ResNet. If testing goes well then we should have a solution during February but please do not upgrade to Vista before we have published the latest version of VSE 8.5i